The objective of this conference is to test new scientific ideas on the prevention of cancer by sharing them and discussing them with a larger group of diverse scientists and physicians who have a professional interest in this subject. It is now clear that cancer often originates in a mutagenic event (one that changes DNA sequences) but the expression of the tumorous character depends on many subsequent events. Agents that can neutralize or inactivate dietary mutagens or prevent subsequent tumor promoters from functioning is likely to reduce the incidence of cancer. Some of these agents may now have been recognized. This conference will consider some of the major ones. The first session will deal with Mutagens and Antimutagens. The second session will be on the anticarcinogenic effects of Selenium and Vitamin E. This day will be summarized by a panel discussion on the "Activation and Deactivation of Carcinogens". The third session will consider Carotenoids and Retinoids. The last session will deal with Dietary Fats of various types. The final roundtable discussion will consider "Future Research Strategies".